1. Technical Field
The present disclosure relates to a wireless network construction system, and particularly to a wireless network construction system capable of improving flexibility in an installation place of a wireless node, and a wireless node installation support terminal.
2. Related Art
The following references relate to a network construction system of an ad hoc wireless network in the—related art.    Japanese Unexamined Patent Publication 1: JP-A-2002-124955    Japanese Unexamined Patent Publication 2: JP-A-2004-146988    Japanese Unexamined Patent Publication 3: JP-T-2004-260740    Japanese Unexamined Patent Publication 4: JP-A-2006-270150
FIG. 13 is a configuration block diagram showing one example of a conventional ad hoc wireless network. In FIG. 13, numerals 1, 2, 3, 4, 5 and 6 are wireless nodes for constructing an ad hoc wireless network and performing a communication through the wireless network.
More concretely, each of the wireless nodes 1 to 6 includes: a wireless communication means for conducting a wireless communication through the constructed ad hoc wireless network; a storage means for storing a program, various parameters, etc.; and an operation control means for controlling all the wireless nodes by reading out and executing the program stored in the storage means.
However, an operation as the whole wireless node will hereinafter be described without referring to a configuration of each of the wireless nodes 1 to 6 for a brief description.
The wireless node 1 is mutually connected to the wireless node 2 using a wireless network line “CN01” (hereinafter simply called a wireless line) in FIG. 13, and is mutually connected to the wireless node 3 using a wireless line “CN02” in FIG. 13.
Also, the wireless node 2 is respectively mutually connected to the wireless node 4 and the wireless node 5 using wireless lines “CN03” and “CN04” in FIG. 13. Further, the wireless node 3 is mutually connected to the wireless node 6 using a wireless line “CN05” in FIG. 13.
A wireless network construction system of the ad hoc wireless network as shown in FIG. 13 will herein be described with FIGS. 14, 15, 16, 17, 18 and 19.
FIG. 14 is a flow diagram for explaining an operation of a newly installed wireless node, and FIG. 15 is a flow diagram for explaining an operation of a previously installed wireless node, and FIGS. 16, 17, 18 and 19 are explanatory diagrams for explaining a state of wireless network construction.
In an ad hoc wireless network (hereinafter simply called a wireless network), conventionally, the wireless network is constructed in a self-growth manner by an unspecified number of wireless nodes, so that a newly installed wireless node requires processing for participating in the existing wireless network.
In “S001” in FIG. 14, a newly installed wireless node decides whether or not to participate in the existing wireless network. In the case of deciding to participate in the existing wireless network in “S001” in FIG. 14, the newly installed wireless node performs a procedure of participation in the wireless network via a previously installed and adjacent wireless node using wireless communication in “S002” in FIG. 14.
Meanwhile, in “S101” in FIG. 15, the previously installed wireless node decides whether or not there was a request for participation in the wireless network from the newly installed wireless node, and in the case of deciding that there was the request for participation, the previously installed wireless node allocates and distributes a network address to the newly installed wireless node in “S102” in FIG. 15.
Then, as necessary, the previously installed wireless node performs distribution of a key for encryption or security authentication processing to the newly installed wireless node in “S103” in FIG. 15, and the previously installed wireless node synchronizes time of the newly installed wireless node in “S104” in FIG. 15.
For example, as shown in FIG. 16, when it is assumed that a wireless node 2 is newly installed and a wireless node 1 is previously installed, the newly installed wireless node 2 performs a procedure of participation in a wireless network via the previously installed wireless node 1 as shown by “JN11” in FIG. 16, and the previously installed wireless node 1 performs processing of time synchronization, key distribution, authentication, distribution, allocation, etc. of a network address to the newly installed wireless node 2, and the newly installed wireless node 2 establishes a wireless line as shown by “CN01” in FIG. 17.
When a wireless node 3 is newly installed in the wireless network constructed thus, the newly installed wireless node 3 performs a procedure of participation in the wireless network via the previously installed wireless node 1 as shown by “JN21” in FIG. 17, and the previously installed wireless node 1 performs processing of time synchronization, key distribution, authentication, distribution, allocation, etc. of a network address to the newly installed wireless node 3, and the newly installed wireless node 3 establishes a wireless line “CN02” in FIG. 18.
Similarly, newly installed wireless nodes 4 and 5 perform procedures of participation in the wireless network on the previously installed wireless node 2 as shown by “JN31” and “JN32” in FIG. 18, and the previously installed wireless node 2 performs processing of time synchronization, key distribution, authentication, distribution, allocation, etc. of network addresses to the newly installed wireless nodes 4 and 5, and the newly installed wireless nodes 4 and 5 respectively establish wireless lines “CN03” and “CN04” in FIG. 19.
Finally, a newly installed wireless node 6 performs a procedure of participation in the wireless network via the previously installed wireless node 3 as shown by “JN41” in FIG. 19, and the previously installed wireless node 3 performs processing of time synchronization, key distribution, authentication, distribution, allocation, etc. of a network address to the newly installed wireless node 6, and the newly installed wireless node 6 establishes a wireless line “CN05” in FIG. 13.
Thus, the newly installed wireless nodes perform the procedures of participation in the wireless network via the previously installed and adjacent wireless nodes, so that the wireless network can be constructed in a self-growth manner.
However, in the conventional example shown in FIG. 13, the newly installed wireless node is required to access the previously installed and adjacent wireless node using wireless communication, so that there was a problem that the wireless node can be installed in only a place capable of surely conducting the wireless communication with the previously installed wireless node and an installation place is restricted in the case of installing a new wireless node.
Further, it is difficult for an on-site operator to decide whether or not wireless communication with the previously installed wireless node can surely be conducted in a location in which a wireless node attempts to be installed, and there has been further a problem that it becomes difficult to determine the installation place of the wireless node.
Also, there has been problems that distribution of a key for encryption or security authentication processing to a newly installed wireless node which is performed by the previously installed wireless node requires complicated processing and causes decrease in performance of a wireless network due to an increase in communication traffic.
Further, there has been a problem that a mechanism becomes complicated in time synchronization due to a factor such as instability of wireless communication environment although time synchronization between each of the wireless nodes is important in sleep time control etc. for electric power saving.